Politeness and civility are similar, but distinct.
The purpose of politeness is to show respect for the people you are now interacting with by acting pleasantly.
The purpose of civility is to create the conditions that allow civilization to advance and prosper. While inoffensive behavior toward other citizens often helps, it is not enough. Civility requires engaging in civic dialogue, and fulfilling your role as a citizen. Because a strong democracy requires an informed citizenry, civility—at least for citizens participating in a representative government—requires being informed.
The citizenship requirements of civility extend beyond politeness. At its best, civility requires exercising each of the virtues described in this course. What would civility be without justice, tolerance, wisdom, and good faith? At its least, it requires some intuition for those virtues.
Civility requires you to be civilized, politeness only requires that you act civilized for now.